This study will examine relationships between pregnancy, cesarean section (CS) and other abdominal surgery, trunk and abdominal muscle deficiency, and degenerative spondylolisthesis (DS) in older females. The key question is whether pregnancy and/or CS mediated trunk muscle deficiency could be a precipitating factor in the development of DS later in life. Three specific aims are to determine whether: (1) parity/CS/other abdominal surgeries are associated with DS, (2) trunk muscle deficiency is associated with DS, and (3) parity/CS/other abdominal surgeries are associated with trunk muscle deficiency. The costs associated with the treatment of degenerative low back disease make it one of the top 5 most expensive conditions in the American healthcare economy. DS is considered one of the major causes of low back pain among the older population. Women suffer from DS at a 3-9 times higher rate than men, as yet, without a clear explanation. Previous studies documented relationships between pregnancy and low back pain, and suggested abdominal muscle deficiency as an underlying cause. Of special concern is the effect of CS. The rates of CS rose three-fold over the last 3 decades and may cause significant public health problems regarding DS in coming years. We propose to conduct a case-control study of 200 DS patients and 200 age-matched (in 5 year age groups) controls, including a more detailed assessment of trunk muscle function in 80 DS and 80 matched control subjects. Group designation will be based on a DS diagnosis from a sagittal view x-ray. The 400 subjects will be administered a detailed questionnaire regarding their parity, CS, previous surgeries, and other potential covariates. A subset of 80 subjects from each group will in addition undergo a physical examination of their abdominal and trunk muscle function and quantitative assessment of motor control. Physical exam will include abdominal muscle and hip extension tests. These tests examine the ability of the abdominal and paraspinal muscles to stabilize pelvis and the lumbar spine during simple hip flexion and extension maneuvers. Motor control tests will quantify muscle reflex latencies in response to sudden trunk perturbations, and postural control while balancing on an unstable seat. Both delayed muscle reflex responses and poor postural control are associated with low back pain and constitute predisposing risk factors to future low back problems. Poor motor control could lead to spine instability, chronic problems and degenerative changes in the spine over time. All measures will be quantified (continuous or categorized) and used in the regression and chi-square analyses to test the hypotheses. Innovative aspects of this proposal comprise of quantifying muscle function objectively and documenting variables related to parity in women with and without DS, which gives a better chance of finding any relationships that might exist. PUBLIC HEALTH RELEVANCE: The costs associated with the treatment of degenerative low back disease make it one of the top 5 most expensive conditions in the American healthcare economy. Women suffer from DS at a 3-9 times higher rate than men, as yet, without a clear explanation. If the number of childbirths and cesarean sections predisposes women to this condition later in life, proactive planning of effective intervention strategies and educational campaigns would be prudent.